Means for preventing entrainment of liquid refrigerant with refrigerant gas



Jan. 1, 1952 E. R. MAGNUS 2,580,805 MEANS FOR PREVENTING ENTRAINMENT OF LIQUID REFRIGERANT WITH REFRIGERANT GAS Filed April 23, 1949 INVENTOR EDWARD R. MAGNUS ATTORNEY Patented Jan. 1, 1952 MEANS FOR PREVENTING ENTRAINMENT OF LIQUID BEFRIGERANT WITH REFRIG- EBANT GAS Edward R. Magnus, St. Louis, Mo., assignor to Snowhill Manufacturing Company, St. Louis, Mo., a corporation of Missouri Application April 23, 1049, Serial N 0. 89,281

This invention relates to certain new and useful improvements in refrigeration systems.

It is the primary object of the present invention to provide a refrigeration system having extremely high K factor and being otherwise extremely efficient in construction and opera- 'tion.

It is a further object of the present invention to provide a refrigeration system which is economical in cost of construction, maintenance, and operation.

It is a further object of the present invention to provide a refrigeration system having unique means for preventing entrainment of parts presently described and pointed out in the claims.

In the accompanying drawing:

Figure 1 is a diagrammatic view of a refrigeration system constructed in accordance with and embodying the present invention;

Figure 2 is a fragmentary vertical sectional view of a modified form of sump constructed in accordance with and embodying the present invention; and

Figure 3 is a schematic view of a refrigeration system illustrating more particularly the application of the present invention to a plate type cooler.

Broadly speaking the present invention resides in a refrigeration system consisting of a suitable evaporator provided with or connected to a sump-like tank vessel or chamber which is adapted to receive liquid refrigerant under pressure directly from a conventional condenser-compressor system. The influx of liquid refrigerant is controlled by a suitable expansion valve, so that the liquid refrigerant is cooled and the flash gas, resulting from its entry into the sump-like chamber, is returned to the suction side of the compressor. The cold liquid refrigerant from the sump-like chamber is pumped up to a header which is a part of a heat exchange unit in which the cooling effect is achieved. The liquid refrigerant is distributed from the header over the heat exchange surfaces in a continuously mov- 6 Claims. (Cl. 62 115) ing unbroken film having substantial mass and a certain portion of the liquid refrigerant will evaporate from the surface of the film, the remaining volume of the liquid flowing back into the sump-like chamber. An auxiliary refrigeration coil with separate temperature controls is located between the cooler and the sump, so that this region of the system is maintained at a lower temperature than the temperature of the gaseous refrigerant in the cooler, and insures complete condensation of any gas which may be entrained with the liquid flowing back into the sump, so that all possibility of gaseous entrainment or vapor locking is effectively prevented.

Referring now more specifically and by reference characters to the drawing, I designates a horizontal type shell and tube cooler provided at its ends with vertical tube sheets 2 for supporting a nest of spaced horizontal heat exchange tubes 3 opening at their opposite ends to tubechambers 4 enclosed by conventional drum heads 5, the latter being provided with conduit pipes 6 through which the fluid to be cooled may be pumped into and withdrawn from the chambers 4 and thus caused to flow through the tubes 3. Enclosed within the shell I between, the tube sheets 2 is an evaporator space I and in the upper region thereof is a horizontally extending refrigerant distribution header 8 provided with a lurality of spaced apertures 9 through which the refrigerant may descend in a shower over the surfaces of the tubes 3.

Suitably mounted beneath the shell I is a sump vessel I0 connected to the shell I by a vertical pipe II being of a relatively large diameter and. having a hand control valve 92. I-he pipe It opens at its lower end into the upper end of the sump vessel I9 and at its upper end into the evaporator space 7 preferably at the low point of the shell I so that liquid refrigerant collecting in the bottom of the shell i will flow by gravity through the pipe II into the sump vessel I0. Leading from a conventional condenser C is a liquid refrigerant line I 3 provided with a hand control valve I4 and communicating through a conventional float valve I5 to the lower interior portion of the sump vessel It. The condenser C is conventionally connected to a compressor D. Leading out of the lower portion of the sump vessel I0 preferably on the opposite side with respect to the float valve :5 is a refrigerant recirculation line I6 having a hand control valve I I and being connected to the intake side of a refrigerant recirculation pump I8 which in turn discharges into a refrigerant line I9, the latter being provided with a hand control valve 23 and being connected to the upper portion of the shell I so as to discharge liquid refrigerant onto the distribution header 9.

Mounted in and extending through the upper portion of one of the tube sheets 2 below the level of the distribution header 9 is a gas re turn line 2| connected through a hand control valve 22 to the intake side of the compressor D. Similarly, leading out of the upper end of the sump vessel is an auxiliary gas return line 23 connected through a hand control valve 24 to the gas return line 2! outwardly of the hand control valve 22.

Disposed in heat exchange relationship around the pipe H below the hand control valve l2 and also preferably, though not necessarily, around the external walls of the sump vessel i0 is an auxiliary expansion coil 25 which is connected at its intake side through an expansion valve 26 and hand control valve 21 to the condenser C and at its other end the expansion coil 25 is connected through a gas return line 28 and hand control valve 29 to the intake side of the compressor D.

In operation, liquid refrigerant enters the sump vessel It! through the float valve I maintaining a predetermined level of refrigerant in the sump vessel [0. The flash gas which is generated as the refrigerant enters the sump vessel I 0 is drawn back through the compressor through the gas return line 23. The liquid refrigerant is circulated by the pump in substantial volume to the distribution header 9 and is caused to flow downwardly in very substantial volume over the heat. exchange tubes 3 so as to maintain a downwardly flowing continuous and unbroken film which moves over the heat exchange surfaces at substantially high velocity. The excess liquid refrigerant collects in the bottom of the shell I and flows downwardly through the pipe H into the sump vessel I 0 for recirculation by the pump I8.

The expansion valve 26 is set so that the expansion coil 25 will maintain the pipe i and the upper portion of the sump vessel ii! at a substantially lower temperature than the temperature of the return gas flowing out of the top of the shell i through the gas return line 2! thereby immediately condensing any gas particles which may be entrained with the return flow of liquid refrigerant or may for any other reason tend to collect in the pipe H and the upper portion of the sump vessel :0, thus eliminating any danger of flow back of liquid refrigerant through the gas return lines 2i, 23, and preventing any vapor lock condition from being set up to interfere with or reduce the eificiency of the operation of the system.

If desired it is possible to provide a modified form of sump vessel as shown in Figure 2, which is substantially identical in every respect with the previously described sump vessel ii ercept that the external expansion coil 25 is eliminated and instead the sump vessel i3 is provided in one of its side walls with a relatively large opening 30 which is covered by a suitably gasketed and sealed closure plate 3|. Mounted on the closure plate 3! and extending inwardly through the upper gas space 32 of the sump vessel It is an expansion coil 33 having a vertical loop 34 extending axially upwardly into the liquid refrigerant return pipe H. The coil 33 extends through the plate 31 by means of sealed-in connections 35, 36, and is conventionally connected to the condenser-compressor system (not shown).

The modified form of sump vessel It) operates substantially in the same manner as previously described in connection with the sump vessel It). The coil 33 is in this instance also maintained at a lower temperature than the temperature of the return gas in the refrigeration system and the returning liquid which flows downwardly through the pipe I I cascades over the coil 33 and its upwardly extending loop 34 so that any entrained gases will be condensed. The coil 33, furthermore, functions to condense any relatively warm gases which might tend to collect in the upper portion of the sump vessel l0.

If desired the present invention may be applied to or used in connection with a plate type cooler 31, as shown in Figure 3, in which the sump vessel l0, identical in every respect with the previously described sump vessel I0, is connected by a refrigerant supply line 38 and a refrigerant return line 39 to the plate cooler 37. This system is provided with only one gas return line 40 which is connected through a hand controlled valve 4| to the upper portion of the sump vessel II). In this type of installation the sump vessel I0 is again provided with an auxiliary cooling coil 25 which is controlled by an expansion valve 26 set in such a manner as to maintain the desired temperature differential for the purposes heretofore described.

It should be understood that changes and modifications in the form, construction, arrangement, and combination of the several parts of the refrigeration system may be made and substituted for those herein shown and described without departing from the nature and principle of my invention.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. A refrigeration system comprising a compressor, a condenser operatively connected to the compressor, an evaporator operatively connected to the suction side of the compressor and having a sump, connection means for connecting the upper end of the sump to the evaporator, means for introducing liquid refrigerant from the condenser to the sump, means for circulating the liquid refrigerant from the sump to the evaporator, and auxiliary means located in heat exchange relation to the connection means for creating a cold zone between the evaporator and the lower portion of the sump, the temperature of which is substantially lower than the temperature of the gaseous refrigerant returning to the compressor from the evaporator.

2. A refrigeration system comprising a compressor, a condenser operatively connected to the compressor, an evaporator operatively connected to the suction side of the compressor and having a sump connection means for connecting the upper end of the sump and the evaporator, a float valve for introducing liquid refrigerant from the condenser to the sump, means for circulating the liquid refrigerant from the sump to the evaporator, and auxiliary means located in heat exchange relation to the connection means for creating a cold zone between the evaporator and the lower portion of the sump, the temperature of which is substantially lower than the temperature of the gaseous refrigerant returning to the compressor from the evaporator.

3. A refrigeration system comprising a compressor, a condenser operatively connected to the compressor, an evaporator operatively connected to the suction side of the compressor and having a sump connection means for connecting the upper end of the sump and the evaporator, means for introducing liquid refrigerant from the com denser to the sump, means for circulating the liquid refrigerant from the sump to the evaporator, and an auxiliary evaporator coil located in heat exchange relation to the connection means for creating a cold zone between the evaporator and the lower portion of the sump, the temperature of which is substantially lower than the temperature of the gaseous refrigerant returning tothe compressor from the evaporator.

4. A refrigeration system comprising a compressor, a condenser operatively connected to the compressor, an evaporator operatively connected to the suction side of the compressor and having a sump, means-for introducing liquid refrigerant from the condenser to the sump, means for circulating the liquid refrigerant from the sump to the evaporator, and an auxiliary evaporator mounted in heat exchange relation to the sump and connected to the condenser for creating a cold zone, the temperature of which is substantially lower than the temperature of the gaseous from the condenser to the sump, means for circulatingthe liquid refrigerant from the sump to the evaporator. and an auxiliary evaporator mounted in the upper portion of the sump and connected to the condenser for creating a cold zone, the temperature of which is substantially lower than the temperature of the gaseous refrigerant returning to the compressor from the evaporator.

6. A refrigeration system comprising a compressor, a condenser operatively connected to the compressor, an evaporator operatively connected to the suction side of the compressor, a sump vessel connected to and depending from the evaporator by a pipe, means for introducing liquid refrigerant from the condenser to the sump, means for circulating the liquid refrigerant from the sump to the evaporator, and an auxiliary evaporator coil disposed around the pipe for creating, between the evaporator and the sump, a cold zone, the temperature of which is substantially lower than the temperature of the gaseous refrigerant returning to the compressor from the evaporator.

EDWARD R. MAGNUS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,117,506 Reinhardt May 17, 1938 2,223,900 Pownall Dec. 3, 1940 2,267,568 Klencker Dec. 23, 1941 

